I'm aware
I'm re-narrowing the range, when i first tried there were less builds in the Mozilla Inbound folder then there are now.
For example, there is a build for 20120726200916 now in the folder between those 2 tinderbox builds.

I can confirm this, as I'm receiving bug reports on my add-on (NoSquint) after users are upgrading to Firefox 17.
I've created a screencast showing the issue and how to reproduce it. It is highly sporadic.
http://youtu.be/yS6ZPymowdo

I should have mentioned: I can reproduce this issue with a clean profile. No add-ons are needed, although with NoSquint the problem is much more consistent (probably because NoSquint modifies the zoom level at a slightly different time during page load than native Firefox does).

A NoSquint user filed a bug at https://github.com/jtackaberry/nosquint/issues/50 which may have more relevant details.
I can reproduce this on Ubuntu 12.10 x86_64, and original submitter of the NoSquint bug was using Ubuntu 11.10 x86. I've received other bug reports by email and have asked them further information about their platform, but considering I'm seeing on different architectures on Linux and Danial saw it on Windows x86, this looks like a platform agnostic bug.

(In reply to Timothy Nikkel (:tnikkel) from comment #11)
> I think this is fixed in nightlies. So it would be good to find out what
> fixed this so we can make sure to uplift it to the right places.
Danial, do you agree this is fixed?